Many people are traveling across the U.S. for the holiday. But others have had to change plans as omicron forces the cancellations of some flights. As of 7:30 p.m. ET Thursday, Delta Air Lines has canceled 84 flights on Christmas Day while United Airlines has canceled 27. More flights have been canceled on Christmas Eve: 121 from United and 79 from Delta, according to flight tracker FlightAware. "The nationwide spike in Omicron cases this week has had a direct impact on our flight crews and the people who run our operation. As a result, we’ve unfortunately had to cancel some flights. … We’re sorry for the disruption,” a statement from United said. The cancellations come as airline industry leaders urge the CDC to shorten its guidance on how long fully vaccinated people with a breakthrough infection should self isolate. Hit the link in our bio for the latest. 📷: @gettyimages, @apnews